Seismic imaging of deep crust.

We introduce here an integral two-dimensional (2-D) scheme for the processing of deep crustal reflection profiles. This approach, in which migration occurs before stacking, is tailored to the unique character of the data in which nonvertically propagating energy is as important as vertically propagating energy. Since reflector depths range beyond 30km, the horizontal displacement of reflections which occurs in migration can be as large as reflector depths; under these circumstances, the common-midpoint (CMP) stack is inadequate. In our scheme, each common-source trace gather is transformed into a set of traces (beams) corresponding to a set of different incidence angles. A correction for wavefront curvature similar to the normal moveout (NMO) correction yields traces (focused beams) which are focused at image points along the direction of arrival.-Authors